An optical module is well known in which a laser beam emitted from a semiconductor laser element is incident on a core of an optical fiber. In the optical module, generally, a laser sub-mount and a fiber sub-mount are arranged on a base pedestal in a housing. Then, the semiconductor laser element is fixed onto the laser sub-mount in a state relative positions of ends of the semiconductor laser element and the optical fiber are correctly fitted to each other, and one end side of the optical fiber is fixed onto the fiber sub-mount.
The other end side of the optical fiber passes through a pipe which projects to an outer peripheral side of the housing and is guided outside the housing, and thus a space between an inner peripheral surface of the pipe and an outer peripheral surface of the optical fiber is sealed without a gap. Further, the pipe is sometimes referred to as a sleeve.
As a method for sealing the inner peripheral surface of the pipe and the outer peripheral surface of the optical fiber, as in the following Patent Document 1, there is a method in which a solder is melted by resistance heating, induction heating, laser heating or the like to be filled in the pipe and then the filled solder is solidified.